Trimethylamine ions, decomposition

The reaction mechanism including the formation and decomposition of quaternary cations may be a general pathway in amine alkylation processes on acidic zeolites. Pouilloux et al. (247), for example, synthesized dimethylethylamine from ethylamine and methanol on an acidic catalyst. At the reaction temperature of 503 K, trimethylamine was determined by gas chromatographic analysis, which can be explained by the formation and decomposition of trimethylethylammonium ions, (CIl3)3N CH2CH3. 

Amide ions have been used for many years to induce proton abstraction reactions and therefore might be expected to react with the tetramethylammonium ion in a similar way. In 1935, the decomposition of tetramethylammonium amide in liquid ammonia was initially reported by Franklin 44> to give trimethylamine and methylamine but no experimental details were given. Later, Hazlehurst, Holliday, and Pass 63> repeated Franklin s experiment 44> and noted that a trace of ethylene was evolved. During later attempts to prepare solid tetramethylammonium amide, a... 

In a previous work, we have shown that the decomposition products are also incorporated in the ZSM-48 framework [14]. The degradation of HM ions was shown to occur by nucleophilic substitution of the trimethylamine groups by NH3 [14], The decomposition is essentially influenced by the synthesis temperature and not by the actual Al content in the hydrogel (sample 11). On the other hand the ehannel dimension of zeolite ZSM-48 iso seems to play an Important role in the decomposition of the HM+ ions. Indeed, in the case of sample 13 which turns to be zeolite EU-1, the HM ions were found intact. We believe that the terminal trimethylammonium groups of each HM " entity can be easily... 

Low-Temperature Decomposition. Over the range of 150°-275°C, a certain amount of intracrystalline water, whether physically adsorbed or hydrating the hydrogen ions, was present. The amount was minimized by pre-evacuating the sample at 150 °C. A displacement reaction of water nucleophile on the TTMA cations forming methanol, trimethylamine— and zeolite hydroxyl groups—can occur. 

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